It happens on PC too so it's definitely not a PS3 specific issue. It didn't bother me much levelling up, but as soon as dungeons start to get a bit deadlier, the issue suddenly slaps you in the face. There are numerous threads about this phenomenon:

http://forum.square-enix.com/ffxiv/t...s-everybody%29
http://forum.square-enix.com/ffxiv/t...serious-issues

As a network engineer you probably have the means to test what IPs your PC (netstat) and PS3 are connecting to. Despite playing on the same world, the servers you connect to can be very different.